NAME

overload::substr - overload Perl's substr() function

SYNOPSIS

 package My::Stringlike::Object;

 use overload::substr substr => sub {
    my $self = shift;
    if( @_ > 2 ) {
       $self->replace_substr( @_ );
    }
    else {
       return $self->get_substr( @_ );
    }
 };

 ...

DESCRIPTION

This module allows an object class to overload the substr core function, which Perl's overload pragma does not allow by itself.

It is invoked similarly to the overload pragma, being passed a single named argument which should be a code reference to implement the substr function.

 use overload::substr substr => \&SUBSTR;

The referred function will be invoked as per core's substr; namely, it will take the string to be operated on (which will be an object in this case), an offset, optionally a length, and optionally a replacement.

 $str->SUBSTR( $offset );
 $str->SUBSTR( $offset, $length );
 $str->SUBSTR( $offset, $length, $replacement );

In each case, whatever it returns will be the return value of the substr function that invoked it.

TODO

• Allow bare method names as well as CODE refs

• Implement LVALUE substr( $str, $offset, $length ) = $replacement.

ACKNOWLEDGEMENTS

With thanks to Matt S Trout <mst@shadowcat.co.uk> for suggesting the possibility, and Joshua ben Jore <jjore@cpan.org> for the inspiration by way of UNIVERSAL::ref.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>